1. Technical Field
The present invention relates in general to a system and method for identifying pallet-level Radio Frequency Identification (RFID) tags when such tags are not readable. In particular, the present invention relates to a system and method that uses statistical data on items within the pallet to determine whether the pallet was received.
2. Description of the Related Art
Radio Frequency Identifiers (RFID) is a means of identifying a unique object that has been tagged with a physical RFID tag by using a radio frequency transmission. Data stored in the RFID tags (also called transponders) is wirelessly transmitted to readers (also called interrogators) in an automated fashion. RFID readers can be stationary or portable, such as handheld readers. One example of a stationary reader is a reader that is installed proximate to a loading dock door to read tags from objects being moved through the dock doors.
RFID tags are affixed to objects. Each RFID tag includes an embedded microchip where information about the object is stored. RFID tags are typically powered by a radio frequency signal sent by the RFID reader. In response to receiving the radio frequency signal, the RFID tag responds by transmitting the identification data stored on the RFID. The radio frequency signals received by the RFID tags may be sent over a range of distances. When many objects are in proximity to a RFID reader, each of the RFID tags that receives the radio frequency signal responds by transmitting the data encoded on the RFID tag.
For example, assume 1,000 RFID-tagged objects are in proximity to an RFID reader that sends a radio frequency signal. Because of positioning of the objects, only 500 of the RFID-tagged objects receive the radio frequency signal, then these 500 RFID tags would transmit identification data back to the RFID reader. Each time the RFID reader sends the radio frequency signal all of the RFID tags that receives the signal responds by transmitting the RFID data irregardless of whether the RFID tags have already been read. Assume that, in our example, the objects are being moved past the reader that periodically sends out the radio frequency signal. As objects are repositioned, some tags that did not originally receive the signal now receive the signal due to their new position in proximity to the RFID reader. Some objects, such as metal or aluminum cans filled with liquid (e.g., soda cans), may act as an insulator that prevents some of the RFID tags from receiving the radio frequency signal even while when the objects are moved. Other tags may not be able to be read because they are surrounded by too many other objects, such as a tag in the middle of a pallet.
As used herein, a pallet is a portable container, or platform, used for storing and moving objects, such as cargo or freight. Pallets are often used to store and move case goods. The cases and other objects stored on an individual pallet may be all of the same type (e.g., a pallet that only has boxes (cases) of oranges) or may have cases or objects of different types (e.g., a pallet that has some cases of oranges, some cases of apples, etc.). A pallet identifier is an RFID tag that uniquely identifies a particular pallet of goods. Each of the cases or objects included in the pallet is also uniquely identified. Using the examples from above, in the first example, a unique pallet identifier would be affixed somewhere on the pallet and each of the cases of oranges would also have RFID tags that uniquely identify each of the cases. Likewise, in the mixed-case example, a unique pallet identifier would be affixed somewhere on the pallet and each of the cases of oranges, apples, etc., would also have RFID tags affixed that uniquely identify the various objects (cases) included in the pallet.
In modern distribution settings, when goods are shipped the distributor (shipper) sends an electronic manifest to the customer (receiver). The electronic manifest details the pallet identifiers as well as the case level identifiers. When the customer receives the shipment, the customer's RFID readers read the tags on the pallets and cases and compares the tags that were read with the data included in the electronic manifest.
A challenge encountered when receiving goods by a receiver is that the pallet RFID tags may be damaged, missing, or be otherwise unreadable. When the receiver matches the pallet-level tags against the electronic manifest, an error condition will be noted and, oftentimes, a dock worker will be asked to manually check for pallet that was not identified by the RFID readers. Depending upon the size of the shipment, this manual check may take a considerable amount of time which is costly both in terms of dock worker productivity as well as dock throughput. Moreover, other shipments waiting to be unloaded may have to wait until the manual inspection has occurred and the missing pallet(s) have been identified.
What is needed, therefore, is a system and method that uses statistical sampling to determine whether a pallet has been received when the pallet-level RFID tag is not read. Furthermore, what is needed is a system and method that allows for changing threshold levels that trigger the successful receipt of a pallet based on the vendor (shipper) as well as the type of goods on the pallet.